Prrsv gp5 based compositions and methods

ABSTRACT

The disclosure includes compositions and methods for the production of an immune response against porcine reproductive and respiratory syndrome (PRRS) virus, or PRRSV. The disclosure is based in part on the use of two or more peptide domains, each with a different sequence, from the PRRSV GP5 protein ectodomain. Compositions and methods comprising polypeptides containing the two or more domains, or nucleic acids encoding them, are described.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of priority from U.S. Provisional Patent Application 60/915,049, filed Apr. 30, 2007, and from U.S. patent application Ser. No. 12/111,871, filed Apr. 29, 2008, and Ser. No. 13/371,166, filed Feb. 10, 2012, all of which are hereby incorporated in their entirety as if fully set forth.

FIELD

This disclosure includes compositions and methods directed to the use of porcine reproductive and respiratory syndrome (PRRS) virus, or PRRSV, polypeptides in the generation of an immune response against the polypeptide, and therefore PRRSV. The disclosure is based in part on the recognition that use of more than one GP5 ectodomain, differing in sequence within an HV-2 hypervariable region, allows generation of a broader immune response against PRRSV than with the use of a single ectodomain. Also disclosed is the use of nucleic acid molecules encoding more than one ectodomain to produce a broader immune response. The description includes compositions containing polypeptides with more than one of the ectodomains, or one or more nucleic acid molecule encoding the polypeptides. Also described are methods to produce an immune response by using polypeptides, nucleic acid molecules encoding them, and/or a composition of the disclosure.

BACKGROUND

PRRSV belongs to the family Ateriviridae, one of animal RNA virus families. Antigenic properties of PRRS viruses, like other RNA viruses, continually change, which results in a most problematic issue in developing an effective vaccine against this disease causing agent. However, there are fundamentals that are not changed in the PRRSV biological system. Importantly, the virus infects a host cell of a multicellular organism for its replication or growth. To infect, the virus must attach to a host cell as part of its life cycle. For attachment, the virus must have a viral receptor recognition protein (RRP) that recognizes one or more specific receptors on the host cell. Last, the host cell's receptor generally does not change because it is usually required for a particular function and so not intended for virus recognition.

But a virus utilizes the cell's receptor to attach or recognize the host cell. Rather than modifying the receptor structure, an organism containing the host cell may produce antibodies that recognize the RRP of the virus to block attachment of virus to the host cell. The antibodies are commonly referred to as neutralizing antibodies (NA). In response, a population of virus often contains or produces modifications to its RRP that allow escape from NA recognition. However, the modifications to the RRP are limited by the fact that the modified RRP must still recognize the cellular receptor for virus attachment. If a modification results in a non-functional RRP, the virus cannot attach, and so cannot replicate or survive.

SUMMARY

The disclosure relates to a three-dimensional arrangement of amino acid residues present in the GP5 protein of porcine reproductive and respiratory syndrome (PRRS) virus, or PRRSV. The arrangement of residues, or polypeptide domain, is present at the N-terminal portion of the GP5 protein, and has been referred to as the ectodomain of the GP5 protein. The disclosure includes use of the domain in the context of a peptide, a polypeptide, a viral particle, or other protein containing composition. In some embodiments, the domain may be present in the form of a recombinant or fusion, peptide or polypeptide. In other embodiments, the domain may be present in, or with, a recombinant viral particle or virus. In further embodiments, a nucleic acid molecule encoding a peptide or polypeptide containing the domain may be used to express the domain for the practice of the disclosure.

The disclosure is based in part on the unexpected discovery that ectodomains that vary in sequence within a previously unappreciated, HV-2 hypervariable region, may be selected for use in the preparation and use of materials to generate an immune response, including a protective response, in an animal against PRRSV. In some cases, at least two PRRSV isolates, each containing a different GP5 protein due to at least one sequence difference within the HV-2 region, are prepared and used to generate an immune response. In other cases, at least three or four PRRSV isolates, each containing a different GP5 protein due to sequence differences at least within the HV-2 region, are prepared and used to produce a protective response.

The disclosure includes the recognition that following a putative signal sequence, the GP5 ectodomain may be viewed as a combination of three regions that precede a putative transmembrane region (or membrane spanning domain or MSD). In sequential order from the N-terminus to the C-terminus of the GP5 protein, the regions are the HV-1 hypervariable region (“HV1”), the conserved region (“CR”), and the HV-2 hypervariable region (“HV2”), which is then followed by a putative transmembrane region (“TR” or MSD). FIG. 1 provides a non-limiting example. Because of the identification of the HV2 as important to the generation of an immune response against PRRSV, the disclosure includes combinations of at least two GP5 ectodomains where they differ in the sequence of the HV2. In some cases, the at least two ectodomains may be present in at least two PRRSV isolates, which may be administered to produce an immune response as described herein.

So in a first aspect, the disclosure includes a combination of at least a first polypeptide domain and a second polypeptide domain, where each domain contains a conserved GP5 motif covalently linked to an HV2 and each domain is antigenic in an animal subject to PRRSV infection. In many embodiments, the linkage is a peptide bond, or amide linkage between amino acid residues in a polypeptide. The GP5 motif and HV2 may be contiguous such that the HV2 follows immediately after the motif in the same polypeptide molecule. In other embodiments, the motif and HV2 may be separated by a linker, such as one or more amino acid residues. In further embodiments, the motif and HV2 may be joined via a chemical linkage other than a peptide bond.

This aspect of the disclosure includes alternative embodiments of the first and second polypeptide domains wherein at least one of the domains is an expanded domain that further contains an HV1 covalently linked to the conserved GP5 motif. This results in at least one domain containing at least three regions: the HV1, the conserved region (CR) containing the conserved GP5 motif, and the HV2, in sequential order. Of course embodiments of the disclosure include combinations of two, or more than two domains, such as three or four domains, where at least two of the domains are expanded domains as described herein. In some cases, each of the domains in a combination is an expanded domain.

In some embodiments, a combination of at least two polypeptide domains is a combination of at least two PRRSV isolates, each of which contains at least one of the domains. In many cases, each of the domains is an expanded domain containing the HV1, the CR, and the HV2, where each domain is different because of at least one sequence difference within the HV2. Of course the domains may optionally contain other sequence differences, such as one or more differences in the HV1.

A combination of domains may be present in a combination of GP5 polypeptides, each of which is present on a PRRSV isolate. Thus the disclosure includes a combination of two or more isolates, each containing a GP5 protein with an expanded polypeptide domain containing a different HV2 sequence as described herein. For example, and in a non-limiting combination of four isolates, a first polypeptide domain is present in a first isolate, a second polypeptide domain is present in a second isolate, a third polypeptide domain is in a third isolate, and a fourth polypeptide domain is present in a fourth isolate. Each of the isolates would differ from the others at least due to a different HV2 sequence in a GP5 protein of the isolate. Of course other sequence differences, such as one or more differences in the HV1, may also be present in the isolates.

In polypeptide based embodiments beyond GP5 protein, the first and second polypeptide domains may be located on the same molecule or on two separate polypeptide molecules. The first and second domains each contain a conserved GP5 motif, represented by the amino acid sequence C(E/S)LNG(T/A), SEQ ID NO: 1. Embodiments of the disclosure include combinations wherein the conserved GP5 motif in each of the two domains is identical. Alternatively, the first and second domains may differ in sequence, and so structure, via the limited variability (four possible sequences) within the conserved motif as indicated by SEQ ID NO: 1.

As described herein, each of the domains in a combination includes an HV2, the sequence of which differs among each of the domains. In cases of an expanded domain, the HV1 sequence may optionally also differ between each of the domains. This is based in part upon the non-limiting view that an expanded domain containing the HV1, the CR, and the HV2 forms a recognition “pocket” which should differ among the different domains of a combination to provide increased diversity when the combination is used to produce an immune response. So by way of a non-limiting example, a sequence difference in the HV2 may result in an alteration in “pocket” structure while sequence changes in both the HV2 and the HV1 may result in a different alteration to the “pocket” structure. And while some embodiments of the disclosure include sequence changes only in the HV2 and the HV1, other embodiments may include sequence changes in the CR.

In many embodiments, the HV2 contains about 8 amino acid residues and/or a conserved portion represented by the tripeptide sequence X₀WL, where X₀ is one of the 20 naturally occurring amino acid residues. This tripeptide sequence may be located at the beginning, or N-terminal end, of the HV2. In some embodiments, the conserved tripeptide sequence comprises the sequence DWL, wherein X₀ is aspartic acid (D). In other embodiments, X₀ is asparagine (N) or any other amino acid residue except aspartic acid (D). In further embodiments X₀ is an acidic amino acid residue, such as glutamic acid (E) or glutamine (Q); a basic amino acid residue, such as arginine (R), lysine (K), or histidine (H); an amino acid residue with an aliphatic sidechain, such as alanine (A) or isoleucine (I) or glycine (G) or leucine (L) or valine (V); an amino acid residue with a hydroxyl containing sidechain, such as threonine (T) or serine (S); or an amino acid residue with an aromatic sidechain, such as tyrosine (Y).

In a second aspect, the disclosure is based upon the antigenicity and/or immunogenicity of the conserved GP5 motif and HV2 in each of the domains in a combination of two or more domains. In some embodiments, the presence of a conserved GP5 motif and an HV2, and optionally an HV1 to form a recognition “pocket”, in each of at least two domains produces antigenic and/or immunogenic, and so the disclosure includes antigenic and immunogenic compositions containing the domains. In additional embodiments, each of the domains is present in a separate polypeptide molecule that is bound or associated with a cell membrane or other lipid bilayer. In some cases, the polypeptide molecule contains a TR, such as a GP5 transmembrane domain, which facilitates association with a membrane or lipid bilayer. In some embodiments, the membrane may be a cell-free membrane or a fragment or portion of a cellular membrane, such as an envelope or coat surrounding a viral particle produced by a cell.

Further compositions include two or more polypeptide molecules that are membrane bound, or membrane associated, such as to a single viral particle or to separate viral particles. The viral particle(s) may be infectious or non-infectious, and independently, it may be replication competent or incompetent. A viral particle may be a PRRSV particle or that of another virus such as a recombinant viral particle that contains the polypeptide molecules. Non-limiting examples of recombinant viral particles that may be used to express a polypeptide of the disclosure include porcine adenovirus and poxvirus.

A viral particle that is both infectious and replication competent may be referred to as a virion. So in some embodiments, the composition may contain two or more polypeptide molecules that are membrane bound, or membrane associated, such as to a single virion or to separate virions. In embodiments of compositions containing two or more virions, such as two or more PRRSV particles, one or more may be a naturally occurring PRRSV particle or isolate that contains a first or second polypeptide domain as described herein. In some cases, more than one, up to all, of the particles are naturally occurring isolates.

Of course additional embodiments of the disclosure include combinations of more than two polypeptide domains or viral particles, each of which contains a conserved GP5 motif and an HV2, optionally with an HV1, as described herein. So compositions comprising additional polypeptide domains beyond a first and second polypeptide domain are expressly within the scope of the disclosure. Of course in such embodiments, the HV2, and optionally the HV1, in each polypeptide domain of a combination differs in sequence, and so structure, from the HV2, and optionally the HV1, in each of the other domains in the combination.

In a further aspect, the disclosure includes a method of preparing a composition described herein. In some embodiments, a method may comprise identifying or selecting at least a first polypeptide domain and a second polypeptide domain, each domain as described herein, and combining the domains to form a composition. In many cases, a method may comprise identifying or selecting at least a first polypeptide molecule containing the first domain and a second polypeptide molecule containing the second domain, and combining the polypeptides to form a composition. In some cases, the combining may comprise addition of one or more pharmaceutically acceptable excipients and/or carriers in forming a composition.

In other embodiments, the identifying or selecting may be among PRRSV isolates based upon the sequence of the HV2 in each isolate. In some cases, the identification or selection may be by detection of the HV2 sequence along with one or more other portions of the GP5 molecule, such as the conserved motif or the HV1. One non-limiting example of a detection method includes use of an antibody that recognizes a given HV2 sequence, optionally in combination with, or in the context of, another portion of the GP5 molecule. Other non-limiting detection methods include amino acid sequencing of the HV2 or nucleic acid sequencing of the sequence encoding the HV2.

In some embodiments, the detection may be of PRRSV in a sample of a biological fluid from an animal subject, such as an individual infected with PRRSV. The method may comprise contacting the sample, or a diluted form thereof, with a binding agent which binds at least a portion of the HV2 in a GP5 protein. The sample may be from a porcine subject, but any subject infected by PRRSV, or a PRRSV carrier, may be used. The biological fluid may be any fluid in which GP5 protein and/or PRRSV particles may be detectably present. Non-limiting examples include the bodily secretions of a subject, such as saliva, tears, mucous, nasal discharge, and vaginal secretions as well as other bodily fluids such as blood, serum, plasma, semen, seminal fluid, and urine as well as any fluid component of feces or a fluid extract of feces.

In further embodiments, the identification, selection, or detection may be of, or for, a novel PRRSV isolate that does not have an HV2 with a sequence as disclosed herein. A novel isolate may be advantageously used in a combination of the disclosure, such as with one, two, three, four, or more domain containing PRRSV isolates disclosed herein. A combination with a novel isolate would be expected to be advantageous because it would have a higher likelihood of producing an antibody or immune response which is novel when compared to the response to a combination lacking the novel isolate.

As indicated above, an additional aspect of the disclosure is a method of producing an antibody response (humoral immune response) or an immune response.

In some embodiments, a method may comprise administering a combination of polypeptide domains, as described herein, to an animal subject with an immune system capable of producing the response. While a given response may be viewed as including a response directed to the domains or to polypeptides containing the domains, the disclosure includes generation of a response that also recognizes GP5 in one or more PRRSV isolates. In some embodiments, the antibody response includes the production of one or more neutralizing antibodies. In other embodiments, the immune response includes the production of one or more cellular immune responses, such as a T cell mediated response. In some cases, the antibody response or immune response is a protective response against a PRRSV particle, such as one expressing a GP5 protein containing a polypeptide domain of the disclosure.

In some cases, the antibody response or immune response is against at least two varieties, or strains, of PRRSV that differ in the HV2, such as those likely to be present within a particular geographic region. So embodiments of the disclosure include a response against one or more varieties of a Lelystad isolate prevalent in Europe, one or more varieties of a North American or Korean serotype of PRRSV, or one or more varieties of PRRSV found in Asia or South America.

In additional embodiments, a method of producing an antibody or immune response in a subject may comprise identifying or selecting, as described herein, at least a first polypeptide domain and a second polypeptide domain, followed by administering the selected domains to a subject to produce the antibody or immune response. In some embodiments, the identifying or selecting may be of at least a first polypeptide comprising the first polypeptide domain and a second polypeptide comprising the second polypeptide domain, followed by administering the selected polypeptides to the subject. In many cases, at least one of the first and second polypeptides may be present in a PRRSV isolate. In some cases, each of the polypeptides is present in a PRRSV isolate.

In alternative embodiments, the identifying or selecting may be of at least a first PRRSV isolate comprising the first polypeptide domain and a second PRRSV isolate comprising the second polypeptide domain, followed by administering the selected isolates to the subject. In some embodiments, the identifying or selecting is of at least three or at least four, or more, isolates. In many cases, the selecting is based upon the HV2 sequence in a GP5 protein of the PRRSV isolate. The identification or selection based upon the HV2 sequence may be performed by any suitable method, including, but not limited to, amino acid sequence analysis of the HV2, PCR-based or antibody-based detection of the HV2; or knowledge of the HV2 sequence in a previously characterized PRRSV isolate.

The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the drawings and detailed description, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a comparison of the amino acid sequences of a representative American type PRRSV strain (VR-2332) and a European type PRRSV strain (Lelystad strain, LV). The putative signal sequences of each are identified along with the HV1, “Conserved Region” or CR (containing the conserved GP5 motif), and the HV2 (underlined). A representative, and non-limiting starting position for the HV1 is also indicated.

FIG. 2 is a schematic representation of groups of PRRSV isolates as disclosed herein.

FIG. 3 shows an alignment of a portion of the GP5 ectodomain sequence, including the conserved GP5 motif and the HV2, from publicly accessible PRRSV sequences. The NCBI (National Center for Biotechnology Information) accession numbers corresponding to the sequences are indicated along with isolates. The isolates include both North American and European strains as well as other types.

FIG. 4 illustrates GP5 protein mediated interactions between PRRSV and a host pig cell.

FIG. 5 is a Kyte-Doolittle hydrophobicity plot of the amino acid sequence of GP5 protein. The indicated numbering is from an American isolate. There is a rapid shift to hydrophobic residues at about amino acid residue 62, corresponding to the start of a putative transmembrane region.

FIG. 6 provides the GenBank accession and GI numbers for representative PRRSV GP5 protein coding sequences.

SEQUENCE LISTING

The nucleic and amino acid sequences listed in the accompanying sequence listing are shown using standard letter abbreviations for nucleotide bases, and three letter code for amino acids, as defined in 37 C.F.R. 1.822. Only one strand of each nucleic acid sequence is shown, but the complementary strand is understood as included by any reference to the displayed strand. The Sequence Listing is submitted as an ASCII text file “Sequence_Listing.txt”, created on May 17, 2016, and having a size of approximately 757 KB which is incorporated by reference herein.

DEFINITIONS

As used herein, the terms porcine reproductive and respiratory syndrome (PRRS) virus, or PRRSV, refer to a virus which has been reported to cause PRRS; Mystery Swine Disease (MSD); Swine Infertility and Respiratory Syndrome (SIRS), which was previously known as “blue-eared syndrome”; porcine epidemic abortion and respiratory syndrome (PEARS); Wabash syndrome; mystery pig disease (MPD); swine plague; blue abortion disease or blue ear disease in the United Kingdom; abortus blau in the Netherlands; seuchenhafter spatabort der schweine in Germany; and Heko-Heko disease (Shimizu et al., 1994). Additional alternative names of the virally caused condition include Blue ear disease, Blue-eared pig disease, Enfermedad misteriosa del cerdo, Epidemisch spätabort der sauen, Lane r bing (Chinese), Maladie blue du porc, Maladie mystérieuse du porc, Mystery pig disease, New pig disease, Plague of 1988-1989, Rätselhafte schweinekrankheit, Síndrome disgenésico y respiratorio del cerdo, Síndrome misterioso del cerdo, Syndrom reproductive et respiratoire du porc, Syndrome dysgénésique et respiratoire du porc, and Syndrome HAAT (Hyperthermie-Anorexie-Avortement de la Truie).

The terms “GP5 protein” and “major envelope glycoprotein” of PRRSV as used herein refer to the polypeptide encoded by ORF5 of a PRRSV genome as understood in the art. Representative, and non-limiting, GP5 sequences coding sequences include those identified by the accession and GI numbers provided in FIG. 6. Without being bound by theory, and offered to improve the understanding of the disclosure, GP5 protein encoded by ORF5 of the PRRSV genome is believed to be a receptor recognition protein (RRP) in PRRSV. The ectodomain of GP5 protein starts from about amino acid N30 to about D61 for the American strain and from about D33 to G63 for European strains (see FIG. 1). The typical differences between American-type strains and European strains are (1) the total amino acids for GP5 proteins are 200 and 201, respectively, (2) European strains have a longer signal sequence compared to American strains, and (3) European strains show less variations compared to American strains. The disclosure is based in part upon the analysis, and identification of the HV2 in each, of approximately 1740 GP5 sequences and their respective ectodomains. Representative sequences are shown in FIG. 3. While the disclosure may be practiced with the use of those representative sequences, the disclosure is not limited to them.

The term “HV-1 region” or “HV1” refers to a polypeptide sequence present at the N-terminal end of the conserved region of GP5 as described herein. The region is optionally present in a polypeptide domain of the disclosure. But when present, the sequence may be up to about 14 or more amino acid residues in length, with lengths of 11, 12, 13 and 14 being specifically contemplated. In other embodiments, lengths of about 11, about 9, about 7, about 5, or about 3 or fewer residues may also be used. The disclosure includes embodiments wherein this region varies considerably in sequence. Non-limiting examples of HV1 sequences include those present in FIG. 3.

Amino acid residues in the disclosed sequences may be conservatively substituted, or replaced, by another residue with similar characteristics and properties. As used herein, conservative amino acid substitutions of the disclosure are shown in Table 1 below.

TABLE 1 Definition Amino Acid Symbol Amino Acids with Aliphatic Glycine Gly-G R-Groups Alanine Ala-A Valine Val-V Leucine Leu-L Isoleucine Ile-I Amino Acids with Hydroxyl Serine Ser-S R-Groups Threonine Thr-T Amino Acids with Sulfur- Cysteine Cys-C Containing R-Groups Methionine Met-M Acidic Amino Acids Aspartic Acid Asp-D Asparagine Asn-N Glutamic Acid Glu-E Glutamine Gln-Q Basic Amino Acids Arginine Arg-R Lysine Lys-K Histidine His-H Amino Acids with Aromatic Phenylalanine Phe-F Rings Tyrosine Tyr-Y Tryptophan Trp-W Imino Acids Proline Pro-P

DETAILED DESCRIPTION OF MODES OF PRACTICING THE DISCLOSURE General

The disclosure is based in part on an analysis of current PRRSV genetic information, such as the DNA sequences of the GP5 protein. Sequences of PRRSV isolated from pigs showing clinical PRRS symptoms were also analyzed. The analysis led to the identification of two hyper variable regions, HV-1 and HV-2, where the HV-2 region begins with either an X₀WL tripeptide motif wherein X₀ is one of the 20 naturally occurring amino acid residues as described herein. The analysis also led to the identification of a conserved region in positions I42 to T53 in an American strain, and positions I44 to T55 in a European strain (see FIG. 1).

Existence of a conserved region in the ectodomains among American strains and European strains of PRRSV indicates that the conserved region participates in direct contact between GP5 protein, as a receptor recognition protein, and a receptor on a host cell to be infected by PRRSV. Based on this idea, and without being bound by theory, the two HV regions on either side of the conserved region are believed to serve as “gates” (or structural motifs) that maintain the hydrophobic properties of the conserved region. Previous commentaries on the HV-1 region and the conserved region did not advance the studies of GP5 protein immunogenicity because there were too many variations in the HV-1 area. But in light of the hypervariability in HV-2, it was illogical to expect that HV-2 would participate in interactions between GP5 and a host cell receptor.

The instant disclosure is also based in part on the recognition that variations in the HV-1 region may be considered in combination with HV-2 sequences that display less variation. Therefore, the instant disclosure includes (1) sorting PRRSV isolates based upon HV2 sequence variations to group them based upon immunological similarities; and (2) selecting combinations of PRRSV strains in different groups to make broad spectrum vaccines that provide broader, heterologous protection upon administration. The sorting and selection may optionally include consideration of the HV-1 region. Additionally, the isolates are optionally first attenuated or inactivated prior to their administration as a vaccine or immunogenic composition. Non-limiting examples of attenuation include methods known to the skilled person, such as serial passage in culture, such as in cells or tissue, or passage in animals. Of course the passaging may be conducted in vitro. Non-limiting examples of inactivation include those known to the skilled person, such as heating, irradiation, chemical inactivation treatments

The disclosure includes the optional division of all American strains into two groups based on amino acid position 61. More than 85% of American-type isolates have been reported to include D (Asp) or S (Ser) at position 61. The exceptions (less than 15%) usually have amino acid residues at position 61 other than C (Cys), F (Phe), M (Met), W (Trp), and P (Pro). Therefore, the disclosure includes embodiments wherein the first HV2 residue, corresponding to position 61, is an amino acid residue other than C, F, M, W, and P. In some embodiments, that residue is selected from A (Ala), G (Gly), V (Val), L (Leu), I (Ile), S (Ser), T (Thr), N (Asn), E (Glu), Q (Gln), R (Arg), K (Lys), H (His), or Y (Tyr). In alternative embodiments, however, that residue is selected from C, F, M, W, or P.

The disclosure includes the optional classification into two groups for American strains; Group D and Group S, with eight sub-groups each (D-1 through D-8 and S-1 through S-8, respectively) based on observed sequence information. The disclosure further includes division of all European strains into eight (8) subgroups (E-1 through E-8) based on observed sequence information. These groupings are illustrated in FIG. 2.

The groups and subgroups are the basis for some embodiments of the disclosure, where a combination of at least a first and second polypeptide domain (each containing a conserved GP5 motif covalently linked to an HV2 as described herein) from different groups or subgroups, may be selected and used to produce a composition or vaccine that produces a broader antibody or immune response than with use of the polypeptide domains separately (or individually). In some embodiments, a combination of two to four, or more, polypeptide domains is used in the practice of the disclosure. In further embodiments, the use of a domain from one group or subgroup may result in the production of an antibody or immune response against more than one domain from the same group or subgroup.

Non-limiting examples of the disclosure include combinations of at least four domains, wherein each of the four is selected, without duplication, from one of the 24 subgroups described herein as D-1 through D-8, S-1 through S-8, and E-1 through E-8. A rough approximation of the number of possible combinations is provided by the mathematical formula (24×23×22×21)/(4×3×2×1), or about 10,600. But in some embodiments, the number of possible combinations are reduced significantly where each combination contains at least one domain from each of the Group D and Group S subgroups as well as one from E-1 through E-8. A rough approximation of such an example is provided by the formula (8×8×8×21)/(4×3×2×1), or about 448. In other embodiments where only Group D and Group S subgroups are used, the number of possible combinations is also reduced. Similarly, embodiments where four domains from E-1 through E-8 are used, the number of possible combinations are further reduced.

More generally, a composition or vaccine of the disclosure may include at least one polypeptide domain from each of the D and S groups as described herein. So a combination of two domains may have one from each of the D and S groups. In other embodiments, a composition or vaccine may include any combination of a D subgroup domain and/or any combination of an S subgroup domain. So a combination of two domains may have both from Group D or both from Group S or one from each group. In many embodiments, the polypeptide domains used in a combination is present in the GP5 protein of a PRRSV isolate that is used as a composition or vaccine of the disclosure. Therefore, the disclosure also includes identification and classification of PRRSV isolates into the same groups and subgroups described herein based upon the HV-2 sequence in the GP5 protein. The classified isolates may then be selected as disclosed.

As additional non-limiting examples, a composition or vaccine of the disclosure may contain

an isolate or domain from the D-1 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup;

an isolate or domain from the D-2 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup;

an isolate or domain from the D-3 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup;

an isolate or domain from the D-4 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup;

an isolate or domain from the D-5 subgroup and an at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup;

an isolate or domain from the D-6 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup;

an isolate or domain from the D-7 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup; or

an isolate or domain from the D-8 subgroup and at least one or more (such as two or three or more) isolates or domains from any other D subgroup or any S or E subgroup.

Alternatively, a composition or vaccine of the disclosure may contain

an isolate or domain from the S-1 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup;

an isolate or domain from the S-2 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup;

an isolate or domain from the S-3 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup;

an isolate or domain from the S-4 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup;

an isolate or domain from the S-5 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup;

an isolate or domain from the S-6 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup;

an isolate or domain from the S-7 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup; or

an isolate or domain from the S-8 subgroup and at least one or more (such as two or three or more) isolates or domains from any other S subgroup or any D or E subgroup.

Similarly, embodiments of the disclosure include a composition or vaccine of the disclosure may contain

an isolate or domain from the E-1 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup;

an isolate or domain from the E-2 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup;

an isolate or domain from the E-3 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup;

an isolate or domain from the E-4 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup;

an isolate or domain from the E-5 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup;

an isolate or domain from the E-6 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup;

an isolate or domain from the E-7 subgroup and at least or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup; or

an isolate or domain from the E-8 subgroup and at least one or more (such as two or three or more) isolates or domains from any other E, D, or S subgroup.

In some embodiments, however, a combination of the disclosure is not a combination of the GP5 ectodomains of VR2332 and LV as described herein. In other embodiments, a combination of the disclosure is not a combination of only GP5 ectodomains with the following sequences bridging the boundary between HV2 and the putative transmembrane region of GP5:

ANKFDWAVET (SEQ ID NO: 7) ANKFDWAVEP (SEQ ID NO: 8) AGEFDWAVET (SEQ ID NO: 9) ADKFDWAVEP (SEQ ID NO: 10) ADRFDWAVEP (SEQ ID NO: 11) or SSHFGWAVET. (SEQ ID NO: 12)

But specifically contemplated embodiments of the invention include combinations of domains wherein both the X₀ residue in X₀WL and at least one additional residue in the HV2 sequence both differ between the domains of a combination.

As described herein, each polypeptide domain (and so each isolate) contains the conserved GP5 motif represented by the amino acid sequence C(E/S)LNG(T/A), SEQ ID NO: 1. So embodiments of the disclosure include domains wherein the GP5 motif is represented by the amino acid sequence CELNGT (SEQ ID NO:2), CELNGA (SEQ ID NO:3), CSLNGT (SEQ ID NO:4), or CSLNGA (SEQ ID NO:5). In other embodiments, the conserved GP5 motif is larger and is represented by the amino acid sequence I(Y/F)(N/D/S/K)(L/S/F/M)(T/P/M)(L/I)C(E/S)LNG(T/A), SEQ ID NO:6, which corresponds to the “Conserved Region” shown in FIG. 1.

Virus Based Compositions

The disclosure is based upon the antigenicity and/or immunogenicity of the conserved GP5 motif and HV2 in a polypeptide domain, used in combination, as described herein. Thus the disclosure includes combinations of viral isolates as described above. Non-limiting examples include combinations of the viral isolates listed in FIG. 3 (based on their sequence deposit information) as they may be classified into the groups and subgroups disclosed herein. In some embodiments, combinations of at least two or more, such as three or four or more, of those isolates are contemplated for use in the practice of the disclosure.

Additionally, the disclosure includes a combination of a viral isolate and a virus particle where each contains a polypeptide of a combination disclosed herein. In other embodiments, two or more virus particles are used. Non-limiting examples of a polypeptide domain containing virus particle of the disclosure include an infectious or non-infectious virus particle, which is independently replication competent or incompetent. Additional non-limiting examples include a virus particle cultured or passaged in vitro; an attenuated virus; and a recombinant viral particle.

In many embodiments, a viral particle is a PRRSV particle with an outer membrane that contains a GP5 protein with a polypeptide domain of the disclosure. In other embodiments, the viral particle may be non-PRRS virus with an outer membrane containing a polypeptide domain, optionally as part of a GP5 protein, as described herein. Further embodiments include a PRRSV or non-PRRSV viral particle with an outer membrane containing two or more of the disclosed polypeptide domains, such as via two or more GP5 proteins with different ectodomains as described herein. In some cases, a viral particle is a PRRSV with a genome that contains multiple copies of GP5 protein encoding ORF5 sequences. Such virus isolates have been previously reported and referred to as an “overproduction mutant” or “high-replication phenotype” PRRSV. The instant disclosure includes such a PRRSV that has been recombinantly modified to contain and express more than one GP5 protein, each containing a polypeptide domain with a different HV2 region as described herein. In other embodiments, a recombinant virus may be an insect virus, such as Baculovirus, which has been previously reported as capable of expressing PRRSV GP5 protein, a porcine adenovirus, or a poxvirus.

In further embodiments, a virus isolate or viral particle is one that is infectious and replication competent, such as a PRRSV isolate or infectious particle. In most cases, the particle contains a genome encoding and capable of expressing GP5 protein after infection in vivo to produce GP5. A particle that is both infectious and replication competent may be referred to as a virion. In alternative embodiments, a particle of the disclosure is infectious and replication incompetent, but optionally capable of intracellularly expressing GP5 proteins.

In embodiments comprising the use of a PRRSV isolate, the isolate may be identified or selected based upon the sequence of the HV2 in an isolate. In some cases, such as that of an isolate represented in FIG. 3 herein, the identification or selection may be based upon review of the sequence information or based upon knowledge of the HV2 sequence in a characterized isolate. In other cases, such as where the isolate has not been previously characterized, the selection may be by detection of the HV2 sequence, such as by use of an antibody that recognizes a given HV2 sequence; sequencing the GP5 coding sequence (ORF5) of the isolate; or purification and amino acid sequencing of the GP5 protein per se. Non-limiting examples of antibody based detection include immunoprecipitation and assays such as ELISA, RIA, and Western blotting. Non-limiting examples of sequencing include dideoxynucleotide-based sequencing of DNA molecules and PCR-based sequencing, including methods based upon reverse transcription of a GP5 encoding RNA molecule followed by PCR. In some embodiments, the selection of an isolate includes detection of the sequence of one or more portions of the GP5 protein beyond the HV2, such as the conserved motif and/or the HV1.

In many embodiments of an antibody based detection method, the antibody does not bind to the GP5 protein as found in multiple PRRSV strains and isolates. Instead, the antibody should be sufficiently specific to the HV2 such that it is capable of detecting a particular isolate based in whole or in part on the HV2 sequence or structure. In addition to the use of an antibody, such as a labeled antibody to facilitate its detection, an antibody fragment that binds the HV2 of a PRRSV GP5 protein may also be used. The antibody fragment may be the Fv or Fab region of an HV2 binding antibody; other non-limiting examples include a single chain antibody, including a single chain Fv region and a single chain Fab region. The antibodies and antibody fragments are preferably monoclonal but may be polyclonal in some cases.

In further embodiments, the detection of a PRRSV isolate is by use of a sample of a biological fluid from a porcine subject, such as an individual infected with PRRSV. The method may comprise contacting the sample, or a diluted form thereof, with a binding agent which binds the HV2 of GP5 protein, preferably to the exclusion of other molecules present in the biological fluid. In many embodiments, the subject is a pig, and the sample may be of a bodily fluid or secretion from a pig. Non-limiting examples of pigs that from which samples may be obtained for use with the present disclosure include boar, sow, fattener, and gilt. The pigs may range in age from 1 to about 30, 31 to about 40, 41 to about 50, or 51 to about 60 days or older.

Of course the biological fluid should be a fluid in which GP5 protein and/or PRRSV particles are detectably present. Non-limiting examples include bodily secretions such as saliva, tears, mucous, nasal discharge, and vaginal secretions as well as other bodily fluids such as blood, serum, plasma, semen, seminal fluid, and urine as well as any fluid component of feces or a fluid extract of feces.

Where the biological fluid contains PRRSV particles, detection may be by use of a PCR-based method to detect a GP5 protein encoding nucleic acid molecule, such as a DNA or RNA molecule containing a GP5 protein or a portion of the molecule encoding at least the HV2.

In additional embodiments, the selection and detection may be of, or for, a PRRSV isolate that has a GP5 protein with an HV2 sequence that differs from any disclosed herein or as previously characterized. Such a novel isolate may still be classifiable into one of the groups or subgroups as disclosed herein. Alternatively, such an isolate may not be classifiable into one of the disclosed groups or subgroups and so may be advantageously used as part of a disclosed combination because the novel isolate would have a higher likelihood of producing a novel antibody or immune response.

The disclosure thus includes a method of producing an antibody or immune response in a subject by use of a PRRSV isolate comprising a GP5 protein with an HV2 sequence that differs from any HV2 sequence disclosed herein. The HV2 of the isolate may thus not be any described herein or encompassed by any of the disclosed groups or subgroups. The method may comprise identifying a PRRSV isolate as comprising a GP5 polypeptide molecule containing an HV2 region distinct from any HV2 sequence of FIG. 3, or any D, S, or E subgroup, and administering said isolate to said subject to produce an antibody or immune response in said subject. The identifying or determining of a distinct HV2 sequence may be by any means disclosed herein, including an antibody or nucleic acid based method as non-limiting examples, followed by comparison to the instant disclosure. In some embodiments, the isolate is attenuated or inactivated as described herein.

Polypeptides and Compositions

The disclosure is based upon the antigenicity and/or immunogenicity of a polypeptide domain containing the conserved GP5 motif and HV2 as described herein. The HV2 portion contributes to the antigenicity and/or immunogenicity of the domain such that the use, in combination, of polypeptide molecules containing two different domains, results in the generation of a broader antibody or immune response in comparison to use of only one of the domains. Accordingly, the disclosure includes combinations of two or more polypeptide domains, such as in a composition or vaccine, as well as their use in a method of immunizing a subject.

The nature of a polypeptide domain has been described herein. Generally, the domain contains a conserved GP5 motif covalently linked to an HV2 region. Many embodiments have a peptide bond, or amide linkage, linking the GP5 motif and the HV2 so that they are contiguous when considering the sequence from N-terminus to the C-terminus. Other embodiments include the use of a linker moiety. Non-limiting examples of a linker moiety include a short peptide sequence, such as about 1, 2, 3, 4, or 5 amino acids in length, and a non-peptide linker, such as a short chain of atoms with at least one carbon atom in the chain or other synthetic linker. In cases of a short peptide sequence, the amino acids may be any naturally occurring amino acid, such as the 20 amino acids of Table 1 herein. In some alternative embodiments, the motif and HV2 may be covalently joined via a non-peptide bond linkage, such as a carbon-carbon bond.

With the use of first and second polypeptide domains, the domains may be located on the same polypeptide molecule or two separate molecules. In many embodiments, the domains are located on separate polypeptide molecules, each of which includes a transmembrane domain or other protein domain that allows for association with a lipid bilayer. A transmembrane domain may also be present in a single polypeptide molecule contain both domains. In some embodiments, the transmembrane domain is the putative transmembrane region of a PRRSV GP5 protein as known to the skilled person and as described herein.

In many embodiments, the domains are located on separate GP5 proteins. In numerous other embodiments, the domains have identical sequences in the conserved GP5 motif, such as that represented by CELNGT (SEQ ID NO:2). But even with an identical conserved GP5 motif, the first and second polypeptide domains differ in the HV2 sequence, which accounts for the desired difference in antigenicity and/or immunogenicity between the domains.

In many embodiments of separate GP5 proteins containing the first and second polypeptide domains, each GP5 protein may comprise, from the N-terminus to the C-terminus, a putative signal sequence, an HV-1 hypervariable region, a conserved region (CR) containing the conserved GP5 motif, the HV-2 hypervariable region, a putative transmembrane region, and the remainder of the GP5 protein. In other embodiments, a GP5 protein may lack all or part of the putative signal sequence. Of course polypeptide molecules retaining the antigenic and/or immunogenic properties of the disclosed polypeptide domains, but with fewer GP5 components, may also be used. Non-limiting examples include a polypeptide molecule comprising the HV-1 hypervariable region, a conserved region (CR) containing the conserved GP5 motif, and the HV-2 hypervariable region, optionally with a transmembrane domain as described above.

Generally, a disclosed HV2 region is about 8 amino acid residues in length. In alternative embodiments, the length may be 6, 7, 8, 9, or 10 residues in length. The exact number of residues is unimportant so long as the resultant domain retains the desired antigenic and/or immunogenic activity. In some embodiments, the HV2 begins with the tripeptide sequence X₀WL where X₀ is as defined herein. So in some embodiments, the HV2 is represented by the sequence X₀WLX₁X₂X₃X₄X₅, wherein each of X₀, X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues shown in Table 1, and X₅ is selected from any amino acid residue, with optional exception of C (Cys), F (Phe), M (Met), W (Trp), and P (Pro).

In other embodiments, the HV2 is a D group sequence represented by X₀WLX₁X₂X₃X₄D, wherein the aspartic acid (D) residue (at the end of X₀WLX₁X₂X₃X₄D) may be replaced by any amino acid residue except C, F, M, P, W, S, T, and Y (such as replacement by A, G, V, L, I, N, E, Q, R, K, or H) and where X₀ is as described above, and one of subgroups D-1 through D-8, which are represented by the following

D-1: wherein X₁ is an aliphatic amino acid residue, X₂ is an acidic amino acid residue (or wherein X₁ is an acidic amino acid residue and X₂ is an aliphatic amino acid residue), X₃ is a basic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F);

D-2: wherein X₁ is an aliphatic amino acid residue, X₂ is Ser, Thr, Tyr or an basic amino acid residue (or wherein X₁ is Ser, Thr, Tyr or a basic amino acid residue and X₂ is an aliphatic amino acid residue), X₃ is a basic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F);

D-3: wherein each of X₁ and X₂ is independently an aliphatic amino acid residue, X₃ is a basic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F);

D-4: wherein X₁ is an acidic amino acid residue, X₂ is Ser, Thr, Tyr or a basic amino acid residue (or wherein X₁ is Ser, Thr, Tyr or a basic amino acid residue and X₂ is an acidic amino acid residue), X₃ is a basic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F);

D-5: wherein each of X₁ and X₂ is independently an acidic amino acid residue, X₃ is a basic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F);

D-6: wherein each of X₁ and X₂ is independently one of the 20 naturally occurring amino acid residues, X₃ is an acidic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F);

D-7: wherein each of X₁ and X₂ is independently one of the 20 naturally occurring amino acid residues, X₃ is a non-aromatic amino acid residue with a hydroxyl containing R-group (such as Ser or Thr), and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F); or

D-8: wherein each of X₁ and X₂ is independently either a basic amino acid residue or an amino acid residue comprising an aromatic ring, such as tyrosine (Y), serine (S), threonine (T), or phenylalanine (F), X₃ is a basic amino acid residue, and X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F).

In additional embodiments, the HV2 is an S group sequence represented by X₀WLX₁X₂X₃X₄X₅ (where X₀ is as described above) and one of subgroups S-1 through S-8, which are represented by the following S-1: wherein X₁ is an acidic amino acid residue, X₂ is asparagine (N), X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S;

S-2: wherein each of X₁ and X₂ is independently an acidic amino acid residue except that X₂ is not asparagine (N), X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S;

S-3: wherein X₁ is an aliphatic amino acid residue, X₂ is an acidic amino acid residue (or wherein X₁ is an acidic amino acid residue and X₂ is an aliphatic amino acid residue), X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S;

S-4: wherein X₁ is an aliphatic amino acid residue, X₂ is Ser, Thr, Tyr or a basic amino acid residue (or wherein X₁ is Ser, Thr, Tyr or a basic amino acid residue and X₂ is an aliphatic amino acid residue; or where each of X₁ and X₂ is independently Ser, Thr, Tyr or a basic amino acid residue; or where each of X₁ and X₂ is independently an aliphatic amino acid residue), X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S;

S-5: wherein X₁ is an acidic amino acid residue, X₂ is Ser, Thr, Tyr or a basic amino acid residue (or wherein X₁ Ser, Thr, Tyr or is a basic amino acid residue and X₂ is an acidic amino acid residue except N (Asn)), X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S;

S-6: wherein X₁ is a basic amino acid residue, X₂ is an asparagine (N), X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S;

S-7: wherein each of X₁ and X₂ is independently one of the 20 naturally occurring amino acid residues, X₃ is a basic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is T or Y; or

S-8: wherein X₁ is an acidic amino acid residue, X₂ is an acidic amino acid residue (or wherein X₁ is an acidic amino acid residue and X₂ is an aliphatic amino acid residue, or alternatively wherein X₁ is an aliphatic amino acid residue and X₂ is an acidic amino acid residue), X₃ is an acidic amino acid residue, X₄ is an amino acid residue comprising an aromatic ring, such as phenylalanine (F), and X₅ is S.

In yet additional embodiments, the HV2 is an E group sequence represented by one of subgroups E-1 through E-8 as follows:

the sequence NWLSX₂X₃X₄X₅ (represented by E-1), wherein each of X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acids, and X₅ is an acidic or aliphatic amino acid residue;

the sequence X₀WLX₁X₂X₃X₄X₅ (represented by E-2), wherein X₀ is an acidic amino acid residue except for asparagine (N), each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues, and X₅ is an acidic or aliphatic amino acid residue;

the sequence X₀WLX₁X₂X₃X₄X₅ (represented by E-3), wherein X₀ is a basic amino acid residue, each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues, and X₅ is an acidic or aliphatic amino acid residue;

the sequence X₀WLX₁X₂X₃X₄X₅ (represented by E-4), wherein X₀ is any non-acidic and non-basic amino acid residue, each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues, and X₅ is an acidic or aliphatic amino acid residue;

the sequence NWLSX₂X₃X₄X₅ (represented by E-5), wherein each of X₂, X₃ and X₄ is independently one of the 20 naturally occurring amino acid residues, and X₅ is Serine (S) or Threonine (T);

the sequence X₀WLX₁NX₃X₄X₅ (represented by E-6), wherein X₀ is any amino acid residue except asparagine (N), each of X₁, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues, and X₅ is Serine (S) or Threonine (T);

the sequence X₀WLX₁X₂X₃X₄X₅ (represented by E-7), wherein X₀ is an acidic amino acid residue except asparagine (N), each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues except that X₂ is not asparagine (N), and X₅ is any non-acidic amino acid residue; or

the sequence X₀WLX₁X₂X₃X₄X₅ (represented by E-8), wherein X₀ is any non-acid amino acid residue, each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues, and X₅ is any non-acidic amino acid residue.

The term “non-acidic” refers to an amino acid residue other than an acidic amino acid; and the term “non-basic” refers to an amino acid residue other than a basic amino acid.

In embodiments of separate polypeptide molecules containing the first and second polypeptide domains, the polypeptide molecules may be administered together or separately in the methods disclosed herein. When administered together, they may be formulated as a composition. Optionally, the composition comprises one or more acceptable carriers or excipients or adjuvants as desired by the skilled person.

Methods of Preparation

The disclosure includes a method of preparing polypeptide domains and polypeptide molecules as described herein. In some embodiments, a peptide or short polypeptide may be prepared by use of de nova synthesis, such as by automated chemical methods known to the skilled person. Alternatively, the preparation may be by use of recombinant DNA methods based upon the availability of nucleic acid molecules encoding the polypeptide domains and polypeptide molecules of the disclosure. The sequences of the nucleic acid molecules may be modified by known techniques, such as, but not limited to, PCR-based mutagenesis and de nova synthesis of nucleic acid molecules, such as by automated chemical methods known to the skilled person.

A method based upon the use of recombinant DNA techniques may be used to produce a disclosed polypeptide. Such a method may comprise expressing a nucleic acid molecule in a suitable expression system, such as an in vitro cell culture system or in a producer animal, and isolating the expressed polypeptide from the expression system. The expression system may comprise a nucleic acid sequence encoding a disclosed polypeptide and operably linked to a suitable regulatory or promoter sequence. Non-limiting examples of a suitable cell or cell line include porcine alveolar macrophages, CRL 11171, MA-104, MARC-145, PSP-36, and PSP-36-SAH. A non-limiting example of a producer animal is a pig, such as a boar, sow, fattener, or gilt.

After producing a disclosed polypeptide domain, the method may comprise selecting and/or combining it as a first polypeptide domain with a second polypeptide domain as described herein to form a composition. The combining may comprise adding one or more acceptable carriers, excipients and/or adjuvants to form a composition.

In some embodiments, such as with a PRRSV based nucleic acid molecule, the expression system produces viral particles that incorporate a disclosed polypeptide within the particle's outer membrane. The PRRSV based nucleic acid molecule may be a viral genome that has been modified to express a GP5 protein containing an HV2 region as disclosed herein. In further embodiments, the nucleic acid molecule contains more than one copy of a GP5 protein encoding sequence, where each copy encodes a different HV2 region as described herein. In other embodiments, the expression system is cell-free, such as in the case of a rabbit reticulocyte system.

Other methods of producing PRRSV particles are also provided. In some embodiments, the production comprises selection and/or isolation of PRRSV isolates as described herein. The selection and/or isolation may comprise culturing or passaging an isolate as known to the skilled person or as described herein. In alternative embodiments, the selection may be of an isolate from an infected subject, such as a pig, and further comprise obtaining infectious fluid and/or tissue from the subject for use as a source of an HV2 region as described herein. Non-limiting examples of an infectious fluid and/or tissue include blood, serum, plasma, nasal secretion, semen, seminal fluid, and urine as well as lung tissue, tonsil tissue, lymph node tissue, a fluid component of feces or a fluid extract of feces. In some embodiments, the infectious fluid and/or tissue may be used as part of a disclosed combination. Non-limiting examples include use of a fluid or tissue as an inoculum in combination with a second HV2 region, optionally in a polypeptide molecule or a viral particle as described herein.

Methods of Use

The disclosure includes a method of generating an antibody or immune response in a subject via administration of a disclosed combination of first and second polypeptide domains. In some embodiments, the method comprises administration of a disclosed composition in an amount effective to produce an antibody and/or immune response. In many cases, the administered amount is effective to produce a protected state in a treated subject against a subsequent challenge by one or more PRRSV isolates, such as infection by PRRSV. In some cases, a method may further comprise an additional administration of a disclosed composition as a “booster”. Non-limiting examples of the subject include a sow, a gilt, a pregnant sow, or a pregnant gilt. In some embodiments, the subject is a pig from about 1 to 12 weeks in age, such as about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, or about 11 weeks. In other embodiments, the pig is from about 12 to about 56 weeks or older in age, such as about 14, about 16, about 18, about 20, about 22, about 24, about 26, about 28, about 30, about 32, about 34, about 36, about 38, about 40, about 42, about 44, about 46, about 48, about 50, about 52, or about 54 weeks. In additional embodiments, the pig has been weaned and/or has passed the stage at which maternal antibodies provide adequate protection.

An effective amount of a disclosed combination or composition, as a vaccine, to produce a protected state in a subject, such as a pig, may also be determined by administration of the vaccine to an unaffected pig, followed by challenge with PRRSV isolate. In some cases, the isolate may be purified or isolated in that its virus particles have the same genome or the same GP5 protein or the same GP5 ectodomain. Non-limiting examples of isolates for use in a challenge include those listed in FIG. 3 as well as an infectious bodily fluid or tissue from an animal infected with the isolate. In some embodiments, the challenge may be after about 3 to about 8 weeks after a booster vaccination, and may be with a large or excess amount of PRRSV.

The vaccine or amount thereof is effective if it reduces the severity of any symptoms of PRRSV infection and/or any gross or histopathological change when compared to the results of challenging a non-vaccinated (untreated with the vaccine) pig with the same isolate. Of course the pig should be PRRSV-free, such as a pig that has not been previously exposed to the virus or which has been exposed but symptom-free for a sufficient period of time to identify it as uninfected. Alternatively, the pig may be identified as uninfected by use of an assay to detect the presence of PRRSV or anti-PRRSV antibody in a bodily fluid or tissue sample from the pig.

Non-limiting examples of symptoms of PRRSV infection include fever, respiratory distress, cyanosis, pneumonia, lethargy, sneezing, coughing, eye edema, blue ears, and heart and/or brain lesions. Additionally, the presence of the isolate used in the challenge may be determined by other quantitative or qualitative methods. Non-limiting examples include detection of lung lesions, or virus in a blood or serum sample, in a challenged pig, with or without vaccination, after about 2 days to about 2 weeks. A decrease in lesions in a vaccinated pig, in comparison to an untreated pig, provides a quantitative means to detect infection. Alternatively, detection of virus in the blood or serum of a vaccinated pig indicates that the vaccination may not have been effective while a negative detection of virus indicates that the vaccination may have been effective.

The effective stimulation of immunoprotection in a subject may be mediated by the generation of an antibody and/or immune response after exposure to a combination or composition of the disclosure. Non-limiting examples of the subject may be a pig that has not been previously exposed to PRRSV or a pig that has been exposed to PRRSV or suffering the effects from PRRSV infection. In many embodiments, the production of an antibody response includes the production of neutralizing antibodies against the GP5 protein, including all or part of the HV2 therein. Confirmation of the generation of such antibodies may be performed by assaying blood or serum from a treated animal for the presence of such antibodies. Non-limiting examples of such antibody detection assays include ELISA, RIA, and Western blotting.

The disclosure includes a method of producing an antibody and/or immune response in a subject as described herein. In some embodiments, the method comprises at least i) identifying or selecting a first PRRSV isolate comprising a polypeptide molecule containing a first HV-2 hypervariable region; ii) identifying or selecting a second PRRSV isolate comprising a polypeptide molecule containing a second HV-2 hypervariable region different from said first hypervariable region; and iii) administering the first and second isolates to a subject to produce an antibody and/or immune response in said subject. In some embodiments, the method may include selection of one or more additional isolates with additional different HV-2 regions followed by their administration with the first and second isolates. In other embodiments, the method may include administration of one or more unselected isolates with the first and second isolates.

The amount of the first and second isolates to administer should of course be sufficient to produce a desired antibody and/or immune response. In some embodiments, the administered amount is sufficient to produce a vaccinated or protected state in the subject against subsequent PRRSV infection by one or more isolates.

In some cases, the identifying or selecting may comprise i) amino acid sequence analysis of the PRRSV GP5 ectodomain HV-2 hypervariable region; ii) PCR-based or antibody-based detection of the PRRSV GP5 ectodomain HV-2 hypervariable region; or iii) knowing the PRRSV GP5 ectodomain HV-2 hypervariable region sequence relative to another isolate.

In other embodiments, a method of producing an antibody and/or immune response comprises administration of a first polypeptide (antigenic) domain comprising an HV-2 region selected from D-1, D-2, D-3, D-4, D-5, D-6, D-7, or D-8, and a second polypeptide (antigenic) domain comprising an HV-2 region selected from S-1, S-2, S-3, S-4, S-5, S-6, S-7, or S-8. In many cases, the combination with two or more different polypeptides (antigenic) domains selected from D-1, D-2, D-3, D-4, D-5, D-6, D-7, D-8, S-1, S-2, S-3, S-4, S-5, S-6, S-7 and S-8 is advantageously used in North America.

In other embodiments, the administration comprises two or more polypeptide (antigenic) domains selected from E-1, E-2, E-3, E-4, E-5, E-6, E-7, and E-8. In many cases, this combination is advantageously used in Europe. In additional embodiments, a combination of two or more different polypeptide (antigenic) domains may be selected from the 24 subgroups depending on the PRRSV isolates found in a particular geographic regions. Non-limiting examples include the isolates found in South Korea, China, Japan, Southeast Asia, or South America. In additional embodiments, a combination used in S. Korea, China, or Japan may be the same as one used in North America. In other embodiments, a domain of any of E-1, E-2, E-3, E-4, E-5, E-6, E-7, and E-8 may be excluded from a combination of domains for use in North America or an Asian location.

In further embodiments, a combination of two or more polypeptide (antigenic) domains, or polypeptide molecules or isolates containing them, comprising at least one from each of subgroups detected at a geographic region may be administered in the practice of the disclosure. Administration of the polypeptide (antigenic) domains, or polypeptide molecules or isolates containing them, may be by any suitable means known to the skilled person. Non-limiting examples include injection, intranasal administration, or oral administration, of one or more disclosed isolates or of one or more sample of cells and/or tissue from a PRRSV infected subject.

If administered or applied separately, the domains, or polypeptide molecules or isolates containing them, may be sequentially administered, with an optional time interval between administrations. Non-limiting examples of the time interval include about 1 to about 2 days; about 1, about 3, or about 5 weeks; about 1, about 3, about 4 or about 6 months, or longer. The same time intervals may be used in between a primary administration event and one or more subsequent “booster” events.

Whether administered together or separately, the polypeptide molecule(s) may be membrane bound or membrane associated, such by association with a lipid bilayer. In some cases, the membrane is from a cell, such as a fragment of a cellular membrane. In other embodiments, the membrane is that of a vesicle, such as a liposome, oil-in-water or water-in oil suspension. Non-limiting examples of a cell derived membrane include the outer membrane of a PRRSV particle or other viral particle as described herein.

Kits

The polypeptide domains, polypeptide molecules, and isolates, as well as combinations and compositions comprising them and their methods of use may be embodied in one or more kits produced in accordance with well known procedures. The disclosure thus includes a kit with one or more reagents comprising one or more polypeptide domains, polypeptide molecules, or isolates, as described herein, or a combination or composition comprising them, for use in one or more methods as disclosed herein. Such a kit optionally further comprises an identifying description or label or instructions relating to their its use in one or more method of the present disclosure. Such a kit may comprise containers, each with one or more of the various reagents (typically in concentrated form) utilized in the methods. A set of instructions will also typically be included.

Having now generally described the invention, the same will be more readily understood through reference to the following examples which are provided by way of illustration, and are not intended to be limiting of the present disclosure, unless specified.

EXAMPLES Example 1 Failure of Conserved GP5 Sequence to Generate Protected State

The disclosure is based in part upon the recognition that pigs previously infected with a first isolate of PRRSV can recover but be susceptible to a second isolate where both isolates contain a GP5 protein with the same sequence in the Conserved Region. Non-limiting examples of such incidents are shown in Table 2 below, where each incident involved pigs that recovered from infection with one of the identified isolates (the first of each incident set in the table) were then found to be infected with at least one other isolate (the second of each of incidents 1-3 and 5-7) as indicated. A portion of the GP5 sequence including the ectodomain in each of the isolates is indicated, with the Conserved Region as identified in FIG. 1 underlined and differences in the HV2 region indicated in bold.

TABLE 2 Incident/ Relative position number in GP5 protein Isolate 21 31 41 51 61 #1 VPFCFVALVN ASNNSSSHLQ LIYNLTICEL NGTDWLNKSF D (Group D-7; Q-05- Seq ID 30318 No: 1765) Q-06- VPFCFVALVN ASNNSSSHLQ LIYNLTICEL NGTDWLNKNF D (Group D-6; 15248 Seq ID No: 1766) #2 VPFCFVALVN ASNNSSSHLQ LIYNLTICEL NGTDWLNKSF D (Group D-7; I-03- Seq ID 28077 No: 1767) I-04- VPFCFVALVN ASNNSSSHLQ LIYNLTICEL NGTDWLDKTF D (Group D-7; 32332 Seq ID No: 1768) #3 VPFCLAALVN ADSNSSSHLQ LIYNLTICEL NGTDWLNNHF S  (Group S-1; S-06- Seq ID 20709 No: 1769)_ S-06- VPFCLAALVN ADSNSSSHLQ LIYNLTICEL NGTDWLNNRF G (Group D-5;_ 20720 Seq ID No: 1770) #4 VPFCFAVLAN ASNNSSSHLQ LIYNLTICEL NGTDWLANKF D (Group D-1; M-05-2912 Seq ID No: 1771) M-06- VPFCLVALVN ANSNNSSHLQ LIYNLTICEL NGTDWLNRHF S (Group S-5; 13702 Seq ID No: 1772) M-06- VPFCLVALVN ANSNNSSHLQ LIYNLTICEL NGTDWLNEHF S (Group S-2; 18282 Seq ID No: 1773) #5 VPFCFAALVN ASNNSSSHLQ LIYNLTICEL NGTDWLNEHF S (Group S-2; H-04-10314 Seq ID No: 1774) H-06-14421 VPFCFVALVN ASNNSSSHLQ LIYNLTICEL NGTDWLNKNF D (Group D-6; Seq ID No: 1775) #6 VPFXFAVIVN ANNNSSSHFQ LIYNLTLCEL NGTEWLNKKF D (Group D-4; A-00-19757 Seq ID No: 1776) A-00-53953 VPFWFAVLVD ANSNSSSHFQ LIYNLTICEL NGTDWLNNKF D (Group D-5; Seq ID No: 1777) #7 VPSCFVAPVN ANDNNSSKLQ LIYNLTLCEL NGTDWLAGKF D (Group D-3; G-00-3628 Seq ID No: 1778) G-05-6157 VPFCFAVIVN ASNNSSSHFQ LIYNLTLCEL NGTDWLAEHF N (Group D-1; Seq ID No: 1779)

Based upon a study of such incidents, a discovery was made that antibodies directed against the Conserved Region in a GP5 protein of an isolate are insufficient to provide protection against a subsequent PRRSV. Additionally, the sequences of the HV-1 region did not provide an adequate explanation for the incidents. A majority of the incidents shown include no change in the HV1 sequence. This led to the discovery that the sequence variation in the HV-2 region participates in evading the immune surveillance of an animal previously exposed to a PRRSV with a different sequence in the HV-2 region. Stated differently, the conserved sequence in the GP5 ectodomain as shown above is unable to produce an antibody or immune response that is protective against another PRRSV with a different HV-2 region in the GP5 protein.

This discovery led, in part, to the disclosed combinations, compositions, and methods.

Example 2 Propagation of PRRSV Isolates

Methods for the propagation and maintenance of PRRSV isolates has been previously reported (see for example Meng et al., 1994, J. Gen. Virol. 75:1795-1801 and Meng et al., 1996, J. of Vet. Diag. Invest. 8:374-381). Non-limiting examples include the use of cell line ATCC CRL 11171, which can be grown in monolayers suitable for inoculation with a viral isolate. Alternative cells and cell lines include MA-104, PSP-36, PSP-36-SAH, MARC-145 and porcine alveolar macrophages.

As a non-limiting example, a multiplicity of infection (moi) of about 0.1, 0.5, or 1 may be used followed by incubation for about 48 hours prior to confirmation of infection and viral replication. Confirmation may be by removal of supernatant (culture media) and fixing the cells followed by detection with a labeled anti-PRRSV antibody, such as a monoclonal antibody specific for the N protein (encoded by ORF 7) or an antibody against a particular HV2 region of a GP5 protein as described herein.

Example 3 Virus Isolate Combinations

As described herein, PRRSV isolates may be classified (identified) and selected for use in a combination of the disclosure at least on the basis of the HV2 sequence. The following data shows a portion of the GP5 sequence (including the ectodomain) in each of numerous representative PRRSV isolates, some of which differ in regions outside the ectodomain. The locations of the HV1, conserved region (CR), and HV2 as described herein are indicated at the bottom of the data, with the indication of the start of the HV1 being a non-limiting representative example.

The classification of the sequences into the disclosed Groups is included, and combinations of isolates from different subgroups may be used in the practice of the disclosure. So as one non-limiting example, a combination of a D-4 isolate (Ingelvac-ATP), a D-1 isolate (Ingelvac-MLV or one of MJ-3 to MJ-14), an S-1 isolate (MJ-1 or MJ-2), and a D-3 isolate (MJ-15 or MJ-16) may be used to produce an immune response in a subject as disclosed herein.

Another non-limiting example is a combination of a D-1 isolate (one of MJ-17 to MJ-27), a D-6 isolate (one of MJ-28 to MJ-30), a D-2 isolate (MJ-34 or MJ-35), and a D-3 isolate (such as MJ-36). All other combinations of isolates represented by the data below, and in accordance with the disclosure, are specifically contemplated for preparation and use as described herein.

All Strains including European Strain (LV) (Group D-4; Seq ID No: 188) Ingelvac-ATP LVNANSNSSSHLQLIYNLTLCELNGTDWLKDKFD (Group D-1; Seq ID No: 47) VR-2332 LANASNDSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 47) Ingelvac-MLV LANASNDSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 48) Prime-Pac LVNASYSSSSHLQLIYNLTLCELNGTDWLANKFD (Group S-1; Seq ID No: 1780) MJ-1 LANASSNSSSHLQLIYNLTICELNGTDWLNNHFS (Group S-1; Seq ID No: 1781) MJ-2 LANANSNSSSHLQLIYNLTICELNGTDWLNNHFS (Group D-1; Seq ID No: 47) MJ-3 LANASNDSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 75) MJ-4 LANASNGSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1142) MJ-5 LANASNHSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 055) MJ-6 LANASNNSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1782) MJ-7 LASASNSSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1783) MJ-8 LATPSPSSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1784) MJ-9 LANASNANSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1785) MJ-11 LANASNVNSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1786) MJ-12 LANASNDNSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1787) MJ-13 LANASNSNSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1788) MJ-14 LANASNSNSSHLQLIYNLTLCELNGTDWLADKFD (Group D-3; Seq ID No: 1789) MJ-15 LANASNGNSSHLQLIYNLTLCELNGTDWLAGKFD (Group D-3; Seq ID No: 1790) MJ-16 LANASNSSNSHLQLIYNLTLCELNGTDWLAGKFD (Group D-1; Seq ID No: 1791) MJ-17 LANASNDSSSHLQLIYNLTLCELNGTDWLADKFD (Group D-1; Seq ID No: 1792) MJ-18 LANASNTSSSHLQLIYNLTLCELNGTDWLADKFD (Group D-1; Seq ID No: 484) MJ-19 LANASNNSSSHLQLIYNLTLCELNGTDWLADKFD (Group D-1; Seq ID No: 1793) MJ-20 LANANNTSSSHLQLIYNLTLCELNGTDXLAEKFD (Group D-1; Seq ID No: 1794) MJ-21 LANANNSSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-6; Seq ID No: 1337) MJ-22 LANASNNSSSHLQLIYNLTLCELNGTDWLANQFD (Group D-1; Seq ID No: 1795) MJ-23 LANASSNSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 61) MJ-24 LANASANSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 508) MJ-25 LANASHNSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1796) MJ-26 LANASQNSSSHLQLIYNLTLCELNGTDWLANKFD (Group D-1; Seq ID No: 1797) MJ-27 LANASSNSSSHLQLIYNLTLCELNGTDWLANRFD (Group D-6; Seq ID No: 1798) MJ-28 LANASSDNSSHLQLIYNLTLCELNGTDWLANNFD (Group D-6; Seq ID No: 1798) MJ-29 LANASSDNSSHLQLIYNLTLCELNGTDWLANNFD (Group D-6; Seq ID No: 1799) MJ-30 LASANSINSPHLQLIYNLTLCELNGTDWLAGEFD (Group D-1; Seq ID No: 1800) MJ-31 LASASNNSSSRLQLIYNLTLCELNGTDWLADRFN (Group D-1; Seq ID No: 1801) MJ-32 LADAHSSSSSHLQLIYNLTLCELNGTDWLADRFD (Group D-1; Seq ID No: 1802) MJ-33 LANAGNNSSSHLQLIYNLTLCELNGTEWLAERFD (Group D-2; Seq ID No: 1803) MJ-34 LGSASSNSSSHFQLIYNLTLCELNGTDWLASRFD (Group D-2; Seq ID No: 1804) MJ-35 LVDANNSSSSHFQLIYNLTICELNGTDWLKARFD (Group D-3; Seq ID No: 1805) MJ-36 LVDANNSSSSHFQLIYNLTICELNGTDWLAARFD (Group D-1; Seq ID No: 1806) MJ-37 LVDANGNSSSHLQLIYNLTLCELNGTDWLANRFD (Group D-1; Seq ID No: 1807) MJ-38 LVNANSTSSSHIQLIYNLTLCELNGTDWLGDKFD (Group D-4; Seq ID No: 1453) MJ-39 LVNANSSSSSHIQLIYNLTLCELNGTDWLTNKFD (Group D-1; Seq ID No: 1808) MJ-40 LVNANSSSSSHLQSIYNLTLCELNGTDWLGNKFD (Group D-5; Seq ID No: 1809) MJ-41 LVDANSSSSSHFQLIYNLTLCELNGTDWLNDKFD (Group D-5; Seq ID No: 1810) MJ-42 LVDANSSSSSHFQLIYNLTLCELNGTDWLNEKFD (Group D-5; Seq ID No: 1811) MJ-43 LVNANSSSSSHFQLIYNLTLCELNGTDWLNEKFD (Group D-1; Seq ID No: 44) MJ-44 LVNANSSSSSHFQLIYNLTLCELNGTDWLADKFD (Group D-1; Seq ID No: 464) MJ-45 LVNANSSSSSHFQLIYNLTLCELNGTDWLGNKFD (Group D-4; Seq ID No: 1812) MJ-46 LANANSSSSSHFQLIYNLTLCELNGTDWLDKKFD (Group D-1; Seq ID No: 1813) MJ-47 LVNANSASSSHSQLIYNLTLCELNGTDWLDGKFE (Group D-3; Seq ID No: 1814) MJ-48 LVNANSASSSHSQLIYNLTLCELNGTDWLAGKFE (Group D-1; Seq ID No: 1815) MJ-49 LVNANSTSSSPFQLIYNLTLCELNGTDWLQGKFN (Group D-3; Seq ID No: 1816) MJ-50 IANASSNSSSHIQLIYNLTLCELNGTDWLAGKFD (Group D-1; Seq ID No: 952) MJ-51 IVNANSNSSSHIQLIYNLTLCELNGTDWLADKFD (Group D-1; Seq ID No: 1817) MJ-52 IVNANSNSSSHFQLIYNLTLCELNGTDWLANKFD (Group D-2; Seq ID No: 1818) MJ-53 VVNANSNSSSHFQSIYNLTLCELNGTKWLATKFD (Group D-6; Seq ID No: 1819) MJ-54 LDNANSTSSSHFQSIYNLTLCELNGTEWLAENFD (Group D-1; Seq ID No: 1820) MJ-55 LDNANSTSSSHFQSIYNLTLCELNGTKWLAEHFD (Group D-4; Seq ID No: 1821) MJ-56 LVNANSTSSSHFQSIYNLTLCELNGTDWLKEKFD (Group D-4; Seq ID No: 1822) MJ-57 LVDANSSSSSHFQSIYNLTLCELNGTDWLTERFD (Group D-1; Seq ID No: 1757) MJ-58 LVNANSNSSSHFQLIYNLTLCELNGTDWLAQKFD (Group D-2; Seq ID No: 572) MJ-59 LVNANSNSSSHFQLIYNLTLCELNGTDWLAKKFD (Group D-6; Seq ID No: 1823) MJ-60 LVDANSNSSSHFQLIYNLTLCELNGPDWLKKNFD (Group D-4; Seq ID No: 571) MJ-61 LVNANSNSSSHFQLIYNLTLCELNGTDWLKEKFD (Group D-5; Seq ID No: 1824) MJ-62 LVGANGNSSSHFQLIYNLTLCELNGTDWLDEKFD (Group D-4; Seq ID No: 1825) MJ-63 LVNASSNSSSHFQLIYNLTLCELNGTDWLKNKFD (Group D-4; Seq ID No: 1826) MJ-64 LVNAHSNSSSHFQSIYNLTLCELNGTDWLDKKFD (Group D-4; Seq ID No: 1827) MJ-65 LVNAHDNSSSHFQLIYNLTLCELNGTDWLNKKFD (Group D-4; Seq ID No: 1828) MJ-66 LVNASNTSSSYFQSIYNLTLCELNGTDWLKDKFD (Group D-1; Seq ID No: 1829) MJ-67 LVNASNSSSSHFQLIYNLTLCELNGTDWLQGKFD (Group D-6; Seq ID No: 1830) MJ-68 IVNASNSNSSHLQSIYSLTLCELNGTEWLGKNFD (Group D-6; Seq ID No: 1831) MJ-69 LVNANNSSSSHFQSIYNLTLCELNGTEWLAKNFN (Group D-6; Seq ID No: 1832) MJ-70 LVNASSNNSSHFQLIYNLTLCELNGTEWLAKNFI (Group D-4; Seq ID No: 473) MJ-71 LVNANSSSSSHLQLIYNLTLCELNGTDWLKDKFD (Group D-4; Seq ID No: 1833) MJ-72 LVNANSNSSSHLQLIYNLTLCELNGADWLKDKFA (Group D-1; Seq ID No: 1834) MJ-73 LVNASNSNSSHLQLIYNLTLCELNGTDWLGNKFN (Group D-1; Seq ID No: 1365) MJ-74 LVNANSNNSSHLQLIYNLTLCSLNGTDWLANKFD (Group D-4; Seq ID No: 1835) MJ-75 LASANNNHSSHLQSIYNLTLCELNGTDWLSDKFD (Group S-4; Seq ID No: 1836) MJ-76 LASANGNHSSHLQSIYNLTLCELNGTDWLRSRFS (Group S-7; Seq ID No: 1837) MJ-77 LVGASNTSSSHFQLIYNLTLCELNGTDWLNNHFY (Group D-5; Seq ID No: 1838) MJ-78 IVDANSNSSSHFQLIYNLTLCELNGTDWLNNHFN (Group S-7; Seq ID No: 804) MJ-79 LVDANSNSSSHFQLIYNLTLCELNGTDWLNNHFT (Group D-4; Seq ID No: 1839) MJ-80 PVNANNGSSSYSQLIYNLTICELNGTDWLNSKFD (Group D-2; Seq ID No: 1840) MJ-81 PVNANNGTSSYSQLIYNLTICELNGTEWLGSKFD (Group D-1; Seq ID No: 1841) MJ-82 LVNAANTSSSYSQLIYNLTLCELNGTDWLVNRFD (Group D-3; Seq ID No: 1842) MJ-83 LANANNTSSSYSQLIYNLTLCELNGTDWLVGKFE (Group D-6; Seq ID No: 1843) MJ-84 LANANSTSSSYSQLIYNLTICELNGTDWLDDNFD (Group S-7; Seq ID No: 1844) MJ-85 LVNANSSSSSYSQLIYNLTLCELNGTDWLDKKFY (Group S-5; Seq ID No: 1845) MJ-86 LVNANNTSSSYSQLIYNLTLCELNGADWLKEHFS (Group S-4; Seq ID No: 1846) MJ-87 LVNANNTNSSYSQLIYNLTLCELNGTDWLKGHFS (Group D-7; Seq ID No: 1847) MJ-88 LVNANSTSSSYSQLIYNLTLCELNGTEWLGNSFN (Group S-4; Seq ID No: 1848) MJ-89 LVNANSTSSSYSQLIYNLTLCELNGTEWLGTKFS (Group S-3; Seq ID No: 1849) MJ-90 LVNANSTSSSYSQLIYNLTLCELNGTEWLGEKFS (Group S-8; Seq ID No: 1850) MJ-91 LVNANSTNSSYSQLIYNLTLCELNGTEWLGKNFS (Group S-4; Seq ID No: 1851) MJ-92 LVNANSTNSSYSQLIYKLTLCELNGTEWLGKKFS (Group S-2; Seq ID No: 1852) MJ-93 LVNANSTSSSYSQLIYNLTLCELNGTDWLNEKFS (Group S-2; Seq ID No: 1853) MJ-94 LVNANSTSSSYSQLIYNLTLCELNGTDWLNDKFS (Group S-3; Seq ID No: 1854) MJ-95 LVNANSTSSSYSQLIYNLTLCELNGTDWLDGHFS (Group S-3; Seq ID No: 1855) MJ-96 LVNANSTSSSYSQLIYNLTICELNGTDWLNGQFS (Group S-8; Seq ID No: 1856) MJ-97 LVNANNTSSSYSQLIYNLTICELNGTDWLNGRFS (Group S-3; Seq ID No: 1857) MJ-98 LVNANNTSSSYSQLIYNLTICELNGTDWLNGKFS (Group S-2; Seq ID No: 1858) MJ-99 LVNANSTSSSYSQLIYNLTICELNGTDWLNEHFS (Group S-5; Seq ID No: 1859) MJ-100 LVNASNNSSSYSQLIYNLTLCELNGTDWLNKKFS (Group D-7; Seq ID No: 1860) MJ-101 LVNASNNSSSHLQLIYNLTICELNGTDWLDKTFD (Group D-7; Seq ID No: 1861) MJ-102 LVNASNNSSSHLQLIYNLTICELNGTDWLDKSFD (Group D-7; Seq ID No: 1862) MJ-103 LVNASNNSSSHLQLIYNLTICELNGTDWLNKTFD (Group D-7; Seq ID No: 878) MJ-104 LVNASNNSSSHLQLIYNLTICELNGTDWLNKSFD (Group D-7; Seq ID No: 1863) MJ-105 LVNASNNSSSHLQLIYNLTICELNGTDWLNRSFD (Group D-7; Seq ID No: 1864) MJ-106 LVNASNNSSSHLQLIYNLTICELNGTDWLNESFD (Group D-6; Seq ID No: 1865) MJ-107 LVNASNNSSSHLQLIYNLTICELNGTDWLSNNFD (Group D-7; Seq ID No: 1866) MJ-108 LVNASNNGSSHLQLIYNLTICELNGTDWLNNTFD (Group S-2; Seq ID No: 1668) MJ-109 LVNANSNSSSHLQLIYNLTICELNGTDWLNDHFS (Group S-2; Seq ID No: 768) MJ-110 LVNANSNSSSHLQLIYNLTICELNGTDWLNEHFS (Group S-5; Seq ID No: 461) MJ-111 LVNANSNSSSHLQLIYNLTICELNGTDWLNSHFS (Group S-5; Seq ID No: 949) MJ-112 LVNAHSNSSSHLQLIYNLTICELNGTDWLNKHFS (Group S-1; Seq ID No: 1073) MJ-113 LVNANSSNSSHLQLIYNLTICELNGTDWLNNHFS (Group S-3; Seq ID No: 1867) MJ-114 LVNASNDSSSHLQLIYNLTICELNGTDWLNGHFS (Group S-5; Seq ID No: 1868) MJ-115 LVNASNSSSSNLQLIYNLTICELNGTDWLKNHFS (Group S-1; Seq ID No: 939) MJ-116 LVNASSNSSSHLQLIYNLTICELNGTDWLENHFS (Group S-5; Seq ID No: 1022) MJ-117 LVNANSNSSSHLQLIYNLTICELNGTDWLKNHFS (Group S-4; Seq ID No: 1869) MJ-118 LVNANSNSSSNLQLIYNLTICELNGTEWLGSHFS (Group D-5; Seq ID No: 837) MJ-119 LVNADSNSSSHLQLIYNLTICELNGTDWLNNHFG (Group D-8; Seq ID No: 1870) MJ-120 LVNANNSSSSHTQLIYNLTLCELNGTEWLSHKFD (Group D-8; Seq ID No: 1871) MJ-121 LVNAANSSSSHFQSIYNLTLCELNGTDWLSKKFD (Group D-8; Seq ID No: 1872) MJ-122 LVNANNTSSSHFQLIYNLTLCELNGTDWLKYKFE (Group D-8; Seq ID No: 1873) MJ-123 LVDANSNSSSHFQLIYNLTICELNGTDWLYKHFD (Group E-1; Seq ID No: 1874) MJ-124 FADGNGNNSTY-QYIYNLTICELNGTNWLSGHFE (Group E-1; Seq ID No: 1875) MJ-125 FADGNGNNSTY-QYIYNLTICELNGTNWLSDHFE (Group E-1; Seq ID No: 1876) MJ-126 FADGNDNNSTY-QYIYNLTICELNGTNWLSAHFE (Group E-2; Seq ID No: 1877) MJ-127 FADGNGNNSTY-QYIYNLTICELNGTDWLSAHFE (Group E-8; Seq ID No: 1878) MJ-128 FADGNGNDSTY-QYIYDLTICELNGTHWLSNHFV (Group E-4; Seq ID No: 1879) MJ-129 FADGNGNDSTY-QYIYNLTICELNGTSWLSDHFE (Group E-2; Seq ID No: 1880) MJ-130 FADGSGNNSTY-QYIYNLTICELNGTDWLSGHFN (Group E-3; Seq ID No: 1881) MJ-131 FADGSGNNSTY-QYIYNLTICELNGTKWLSGHFD (Group E-4; Seq ID No: 1882) MJ-132 FADGNGNSSTY-QYIYNLTICELNGTTWLSGHFN (Group E-1; Seq ID No: 1883) MJ-133 FADGNGNSSTY-QYIYNLTICELNGTNWLSGHFN (Group E-6; Seq ID No: 1884) MJ-134 FADGNGNNSTY-QYIYNLTICELNGTDWLSNHFS (Group E-5; Seq ID No: 1885) MJ-135 FADGNDNNSTY-QYIYNLTICELNGTNWLSNHFS (Group E-7; Seq ID No: 1886) MJ-136 FADGNGDSSTY-QYIYNLTICELNGTDWLSSHFG (Group E-7; Seq ID No: 1887) LV FADGNGDSSTY-QYIYNLTICELNGTDWLSSHFG |← HV1 →|← C. Region →|← HV2 →|

All references cited herein are hereby incorporated by reference in their entireties, whether previously specifically incorporated or not. As used herein, the terms “a”, “an”, and “any” are each intended to include both the singular and plural forms.

Having now fully described the invention, it will be appreciated by those skilled in the art that the same can be performed within a wide range of equivalent parameters, concentrations, and conditions without departing from the spirit and scope of the disclosure and without undue experimentation. While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains and as may be applied to the essential features hereinbefore set forth. 

We claim:
 1. An immunogenic composition, comprising: a first separated PRRSV GP5 antigenic polypeptide comprising a first HV-2 hypervariable region; and a second separated PRRSV GP5 antigenic polypeptide comprising a second HV-2 hypervariable region, the second HV-2 region selected to be different from the first HV-2 hypervariable region.
 2. The composition of claim 1, wherein the first HV-2 hypervariable region has a first group sequence, and the second HV-2 hypervariable region has a second group sequence, selected to be different from the first group sequence.
 3. The composition of claim 2, wherein the first HV-2 hypervariable region comprises a first sequence having an amino acid sequence X₀WLX₁X₂X₃X₄X₅, and the first group sequence is one of D1 to E-8, and the second HV-2 hypervariable region comprises a second sequence having an amino acid sequence X₀WLX₁X₂X₃X₄X₅, and the second group sequence is selected from D-1 to E-8; wherein the group sequences D-1 to E-8 are: D-1: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is glycine, alanine, valine, leucine or isoleucine and X₂ is aspartic acid, asparagine, glutamic acid or glutamine, or X₁ is aspartic acid, asparagine, glutamic acid or glutamine and X₂ is glycine, alanine, valine, leucine or isoleucine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-2: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is glycine, alanine, valine, leucine or isoleucine and X₂ is serine, threonine, tyrosine, arginine, lysine or histidine, or X₁ is serine, threonine, tyrosine, arginine, lysine or histidine and X₂ is glycine, alanine, valine, leucine or isoleucine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-3: X₀ is one of the 20 naturally occurring amino acid residues; each of X₁ and X₂ is independently glycine, alanine, valine, leucine or isoleucine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-4: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is aspartic acid, asparagine, glutamic acid or glutamine and X₂ is serine, threonine, tyrosine, arginine, lysine or histidine, or X₁ is serine, threonine, tyrosine, arginine, lysine or histidine and X₂ is aspartic acid, asparagine, glutamic acid or glutamine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-5: X₀ is one of the 20 naturally occurring amino acid residues; each of X₁ and X₂ is independently aspartic acid, asparagine, glutamic acid or glutamine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-6: X₀ is one of the 20 naturally occurring amino acid residues; each of X₁ and X₂ is independently one of the 20 naturally occurring amino acid residues; X₃ is aspartic acid, asparagine, glutamic acid or glutamine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-7: X₀ is one of the 20 naturally occurring amino acid residues; each of X₁ and X₂ is independently one of the 20 naturally occurring amino acid residues; X₃ is serine, X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; D-8: X₀ is one of the 20 naturally occurring amino acid residues; each of X₁ and X₂ is independently serine, threonine, tyrosine, arginine, lysine or histidine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is glycine, alanine, valine, leucine, isoleucine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, lysine or histidine; S-1: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is aspartic acid, asparagine, glutamic acid or glutamine; X₂ is asparagine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; S-2: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is aspartic acid, asparagine, glutamic acid or glutamine; X₂ is aspartic acid, glutamic acid or glutamine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; S-3: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is glycine, alanine, valine, leucine or isoleucine and X₂ is aspartic acid, asparagine, glutamic acid or glutamine, or X₁ is aspartic acid, asparagine, glutamic acid or glutamine and X₂ is glycine, alanine, valine, leucine or isoleucine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; S-4: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is glycine, alanine, valine, leucine or isoleucine and X₂ is serine, threonine, tyrosine, arginine, lysine or histidine, or X₁ is serine, threonine, tyrosine, arginine, lysine or histidine and X₂ is glycine, alanine, valine, leucine or isoleucine; or each of X₁ and X₂ is independently serine, threonine, tyrosine, arginine, lysine or histidine, or each of X₁ and X₂ is independently glycine, alanine, valine, leucine or isoleucine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; S-5: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is aspartic acid, asparagine, glutamic acid or glutamine and X₂ is serine, threonine, tyrosine, arginine, lysine or histidine, or X₁ is serine, threonine, tyrosine, arginine, lysine or histidine and X₂ is aspartic acid, glutamic acid or glutamine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; S-6: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is serine, threonine, tyrosine, arginine, lysine or histidine; X₂ is asparagine; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; S-7: X₀ is one of the 20 naturally occurring amino acid residues; each of X₁ and X₂ is independently one of the 20 naturally occurring amino acid residues; X₃ is arginine, lysine or histidine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is threonine or tyrosine; S-8: X₀ is one of the 20 naturally occurring amino acid residues; X₁ is aspartic acid, asparagine, glutamic acid or glutamine and X₂ is aspartic acid, asparagine, glutamic acid or glutamine, or X₁ is aspartic acid, asparagine, glutamic acid or glutamine and X₂ is glycine, alanine, valine, leucine or isoleucine, or X₁ is glycine, alanine, valine, leucine or isoleucine and X₂ is aspartic acid, asparagine, glutamic acid or glutamine; X₃ is aspartic acid, asparagine, glutamic acid or glutamine; X₄ is phenylalanine, tyrosine or tryptophan; and X₅ is serine; E1: X₀ is asparagine; X₁ is serine; each of X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is aspartic acid, asparagine, glutamic acid, glutamine, glycine, alanine, valine, leucine or isoleucine; E2: X₀ is aspartic acid, glutamic acid or glutamine; each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is aspartic acid, asparagine, glutamic acid, glutamine, glycine, alanine, valine, leucine or isoleucine; E3: X₀ is arginine, lysine or histidine; each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is aspartic acid, asparagine, glutamic acid, glutamine, glycine, alanine, valine, leucine or isoleucine; E4: X₀ is glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, phenylalanine, tyrosine, tryptophan or proline; each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is aspartic acid, asparagine, glutamic acid, glutamine, glycine, alanine, valine, leucine or isoleucine; E5: X₀ is asparagine; X₁ is serine; each of X₂, X₃ and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is serine or threonine; E6: X₀ is any of the 20 naturally occurring amino acid residues except asparagine; X₂ is asparagine; each of X₁, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is serine or threonine; E7: X₀ is aspartic acid, glutamic acid or glutamine; each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues except that X₂ is not asparagine; and X₅ is glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, arginine, lysine, histidine, phenylalanine, tyrosine, tryptophan or proline; and E8: X₀ is glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, arginine, lysine, histidine, phenylalanine, tyrosine, tryptophan or proline; each of X₁, X₂, X₃, and X₄ is independently one of the 20 naturally occurring amino acid residues; and X₅ is glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, arginine, lysine, histidine, phenylalanine, tyrosine, tryptophan or proline.
 4. The composition of claim 1, further comprising an adjuvant.
 5. The composition of claim 3, wherein at least one of the first and second group sequences is D-1, D-2, D-3, D-4, D-5, D-6, D-7 or D-8.
 6. The composition of claim 3, wherein at least one of the first and second group sequences is S-1, S-2, S-3, S-4, S-5, S-6, S-7 or S-8.
 7. The composition of claim 3, wherein at least one of the first and second group sequences is E-1, E-2, E-3, E-4, E-5, E-6, E-7 or E-8.
 8. The composition of claim 3, wherein the first group sequence is D-1, D-2, D-3, D-4, D-5, D-6, D-7 or D-8, and the second group sequence is S-1, S-2, S-3, S-4, S-5, S-6, S-7 or S-8.
 9. The composition of claim 1, further comprising a third PRRSV GP5 antigenic polypeptide comprising a third HV-2 hypervariable region.
 10. The composition of claim 9, wherein the third HV-2 hypervariable region is selected to be different from the first and second HV-2 hypervariable regions.
 11. The composition of claim 9, wherein the third PRRSV GP5 antigenic polypeptide is a separated PRRSV GP5 antigenic polypeptide.
 12. The composition of claim 9, wherein the first HV-2 hypervariable region has a first group sequence, the second HV-2 hypervariable region has a second group sequence different from the first group sequence, and the third HV-2 hypervariable region has a third group sequence different from the first and second group sequences.
 13. The composition of claim 1, comprising isolated first and second PRRSV GP5 antigenic polypeptides.
 14. The composition of claim 1, wherein each of the first and second PRRSV GP5 antigenic polypeptides independently has a length from 14 to 201 amino acids.
 15. An immunogenic composition, comprising a first GP5 antigenic polypeptide domain having a length from 14 to 201 amino acids comprising a first HV-2 hypervariable region having a length of about 8 amino acids, and a second GP5 antigenic polypeptide domain having a length from 14 to 201 amino acids comprising a second HV-2 hypervariable region having a length of about 8 amino acids, the second HV-2 region selected to be different from the first HV-2 hypervariable region, the immunogenic composition being substantially free of intact viral particles.
 16. A method of making an immunogenic composition, comprising: identifying or selecting a first PRRSV GP5 antigenic polypeptide comprising a first HV-2 hypervariable region; purposefully selecting a second PRRSV GP5 antigenic polypeptide that has a second HV-2 hypervariable region different from the first HV-2 hypervariable region; and combining the first and second PRRSV GP5 antigenic polypeptides to form the immunogenic composition.
 17. The method of claim 16, wherein the first HV-2 hypervariable region has a first group sequence, and the second HV-2 hypervariable region has a second group sequence.
 18. The method of claim 17, comprising purposefully selecting the second PRRSV GP5 antigenic polypeptide such that the second group sequence is different from the first group sequence.
 19. The method of claim 16, further comprising adding an adjuvant.
 20. The method of claim 16, further comprising combining a third PRRSV GP5 antigenic polypeptide with the first and second PRRSV GP5 antigenic polypeptides.
 21. The method of claim 20, comprising selecting the third PRRSV GP5 antigenic polypeptide to have a third HV-2 hypervariable region that is different from the first and second HV-2 hypervariable regions.
 22. The method of claim 21, wherein the third HV-2 hypervariable region has a third group sequence, and selecting the third GP5 antigenic polypeptide comprises selecting the third group sequence such that it is different from at least one of the first and second group sequences.
 23. The method of claim 22, wherein the third group sequence is different from both the first and second group sequences.
 24. The method of claim 16, wherein the first PRRSV GP5 antigenic polypeptide is a first separated PRRSV GP5 antigenic polypeptide, and the second PRRSV GP5 antigenic polypeptide is a second separated PRRSV GP5 antigenic polypeptide.
 25. An immunogenic composition made by the method of claim
 16. 